Although there are known a great variety of dampers or shock absorbers, a majority thereof typically comprise common elements: a sleeve (cylinder) having a longitudinal axis and filled with suitable oil, a damper piston (herein further called ‘piston’), and a piston rod (herein further called ‘rod’) fixedly coupled with the piston. The rod and piston are capable of accomplishing a reciprocating movement within the sleeve along the longitudinal axis thereof. Besides the aforementioned elements, a shock absorber can include a housing, typically enclosing the sleeve, and additional external cylinders. The piston partitions the sleeve into two chambers of variable volumes. As a rule, the piston includes a plurality of precisely calibrated orifices for oil cross-flow from one chamber to the other (e.g. see Russian Useful Model 74602). Some dampers may comprise a cavity between the housing and the sleeve, while the sleeve may include orifices for oil cross-flow from a chamber of the sleeve into the cavity.
At present, one-tube gas-oil shock absorbers with a high-pressure gas chamber and two-tubes oil shock absorbers with low-pressure gas support are among widest-spread damper devices. In the related art there is known a shock absorber including an elastic element (spring), a cylinder, a piston, and a rod (U.S. Pat. No. 3,857,307 issued 31 Dec. 1974). It can be applied for improving a damper system of transportation means, wherein the load exerted onto the suspension unit varies within a broad range, which may cause maximal values of the amplitude of piston's oscillations relatively to the middle point on the longitudinal axis of the shock absorber. A drawback of such device is an insufficient increase of force counteracting the movement of piston in the cylinder within the region(s) proximate to the absorber's cap(s). The most similar device found in the related art (further called ‘prototype’) is considered a damper, designed according to Russian Useful Model 74602 that comprises a sleeve, a piston, a piston cap, a rod, a rod cap, wherein the rod and piston are capable of collective displacing within the sleeve along the longitudinal direction of sleeve. The aforementioned prototype shares certain common features with the present invention, but is in fact essentially different in its design principles. The prototype has the following shortcomings:                an insufficient increase of a force counteracting the movement of the piston in the sleeve in the regions proximate to the caps;        underuse of two sealing lateral surfaces during the forward and the reverse travels of the piston, where the piston is located in the sleeve within a vicinity proximate to the piston cap; and        underuse of two sealing lateral surfaces during the forward and the reverse travels of the piston, where the piston is located in the sleeve within a vicinity proximate to the rod cap.        